Tooling for machining systems utilizing supercritical fluids

ABSTRACT

Improvements in tooling for machining systems that utilize machining fluids comprising a supercritical fluid are disclosed. In some embodiments a tool may include a plurality of orifices configured to direct a supercritical machining fluid towards a cutting interface of the tool. In other embodiments, a tool holder may include one or more outlets configured to direct a supercritical machining fluid towards a cutting interface. Moreover, some embodiments, may relate to machining systems including one or more venting channels configured to provide pressure relief for a cavity located behind a tool holder. Embodiments related to machine tools including upstream fluid restrictions for controlling a flow of supercritical machining fluid through a tool are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Application Serial No.16/870,837, filed May 8, 2020, which claims the benefit under 35 U.S.C.§ 119(e) of U.S. provisional application serial number 62/846,022, filedMay 10, 2019, the disclosures of which are incorporated by referenceherein in their entirety.

FIELD

Disclosed embodiments are related to machining systems utilizingsupercritical machining fluids. Some embodiments relate to tooling forsuch machining systems.

BACKGROUND

Machining tools, such as milling systems, lathes, computer numericalcontrol (CNC) systems, robotic drills, and/or machining centers mayemploy machining fluids such as metalworking fluids to provide coolingand/or lubrication during a cutting or forming process. The machiningfluid may be delivered to an interface between a cutting tool and aworkpiece during a cutting or forming process. In some applications, themachining fluid may be delivered externally, such as by routing themachining fluid through a series of pipes and to one or more nozzlesthat direct the machining fluid toward the cutting interface. In otherapplications, the machining fluid may be routed internally to theinterface, such as through a tool holder and/or through a cutting tool(e.g., through one or more channels formed in a cutting tool).

Conventional machining fluids may comprise mixtures including a coolingfluid (such as air, water, liquid carbon dioxide, or liquid nitrogen) tocool a cutting zone and a lubricant (such as oil, a minimum quantitylubrication (MQL) fluid, or synthetic fluids) to lubricate the cuttingzone during a cutting process. In some instances, a machining fluid onlyincluding an oil, emulsion, or a synthetic fluid may be suitable. Insome applications supercritical fluids, such as supercritical carbondioxide (scCO₂) have been utilized as a portion of a machining fluid.

SUMMARY

In one embodiment, a tool for a machining system utilizing asupercritical machining fluid includes a tool body extending from aproximal end of the tool configured to be received in a tool holder to adistal end of the tool. The tool also includes a fluid channel formed inthe tool body having an inlet located in a proximal portion of the toolbody. The inlet is configured to receive the supercritical machiningfluid. The tool further comprises a plurality of orifices formed on anouter surface of the tool body. Each orifice of the plurality oforifices is in fluid communication with the fluid channel, and at leastone orifice of the plurality of orifices is located on a side surface ofthe tool body. Each orifice has a diameter between about 50 microns andabout 500 microns.

In another embodiment, a tool for a machining system utilizing asupercritical machining fluid comprises a tool body extending from aproximal portion configured to be received in a tool holder to a distalend. The tool also comprises a fluid channel formed in the tool bodyhaving an inlet at the proximal end of the tool body and at least onerecess formed on an outer surface of the tool body. The at least onerecess defines at least one surface oriented along a first direction andthe at least one recess is spaced from the distal end of the tool body.The tool also comprises an orifice formed in the at least one surface influid communication with the fluid channel. In such an embodiment, theat least one orifice may be configured to direct supercritical machiningfluid out of the orifice along the first direction.

In yet another embodiment, a tool holder for a machining system includesa tool holder body including a tool receiving region at a first endportion and an attachment interface at a second end portion opposite thefirst end portion. The tool receiving region is constructed and arrangedto receive a tool and secure the tool to the tool holder body. Theattachment interface is constructed and arranged to secure the toolholder to a machining system. The tool holder is configured to berotated during a machining process. The tool holder includes one or moreoutlets positioned proximate to the first end portion of the tool holderbody, and each outlet is configured to direct supercritical machiningfluid towards a cutting interface of the tool.

In one embodiment, a machining system comprises a tool holderconstructed and arranged to receive a tool and secure the tool withinthe tool holder. The tool is configured to deliver a supercriticalmachining fluid to a cutting interface through the tool. A spindle isconstructed and arranged to receive the tool holder, and a cavity formedbetween the tool holder and the spindle is in fluid communication withan exterior of the machining system.

In another embodiment, a tool for a machining system utilizing asupercritical machining fluid includes a tool body extending from aproximal end configured to be received in a tool holder to a distal end.The tool includes an inlet formed in a proximal portion of the toolbody, and the inlet is configured to receive a supercritical machiningfluid. The tool also includes a flow restriction disposed in the toolbody and in fluid communication with the inlet and a fluid channelformed in the tool body. The fluid channel is downstream from and influid communication with the flow restriction. The tool also includesone or more orifices formed on an outer surface of the tool body, andeach orifice of the one or more orifices is in fluid communication withthe fluid channel. In such an embodiment, a flow resistance of the oneor more orifices and the fluid channel is less than a flow resistance ofthe flow restriction.

In another embodiment, a tool for a machining system utilizing asupercritical machining fluid comprises a tool body comprising a fluidchannel. The tool body extends from a proximal end configured to bereceived in a tool holder to a distal end and further comprises one ormore orifices located on an outer surface of the tool body. Each of theone or more orifices is in fluid communication with the fluid channel ofthe tool body and an insert including a flow restriction is disposed ina cavity formed in a proximal portion of the tool body. The flowrestriction is upstream from and in fluid communication with the fluidchannel of the tool body, and a flow resistance of the flow restrictionis greater than a flow resistance of the plurality of orifices and thefluid channel.

In one embodiment, a machining method includes flowing a super criticalmachining fluid through a flow restriction of a tool body into a fluidchannel of the tool body and then expanding the supercritical machiningfluid in the fluid channel. Next, the method includes flowing theexpanded supercritical machining fluid though one or more orificesformed on an outer surface of the tool body. In such an embodiment, aflow resistance of the one or more orifices and the fluid channel isless than a flow resistance of the flow restriction.

An alternate machining method comprises flowing supercritical machiningfluid into an inlet of a tool body, flowing the supercritical machiningfluid through a fluid channel formed in the body, and then flowing thesupercritical machining fluid out of the fluid channel through aplurality of orifices formed on an outer surface of the tool body. Eachorifice has a diameter between about 50 microns and about 500 microns,and at least one orifice of the plurality of orifices is located on aside surface of the tool body.

It should be appreciated that the foregoing concepts, and additionalconcepts discussed below, may be arranged in any suitable combination,as the present disclosure is not limited in this respect. Further, otheradvantages and novel features of the present disclosure will becomeapparent from the following detailed description of various non-limitingembodiments when considered in conjunction with the accompanyingfigures.

It should be appreciated that the foregoing concepts, and additionalconcepts discussed below, may be arranged in any suitable combination,as the present disclosure is not limited in this respect. Further, otheradvantages and novel features of the present disclosure will becomeapparent from the following detailed description of various non-limitingembodiments when considered in conjunction with the accompanyingfigures.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures may be represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a perspective view of a tool, according to some embodiments;

FIG. 2 is a side view of the tool of FIG. 1 ;

FIG. 3 is a perspective view of a tool installed in a machining system,according to some embodiments;

FIG. 4 is a perspective view of a tool, according to some embodiments;

FIG. 5 is another perspective view of the tool of FIG. 4 ;

FIG. 6 is a perspective view of a portion of a machining system,according to some embodiments;

FIG. 7 is a schematic side view of one embodiment of a tool;

FIG. 8 is a schematic side view of another embodiment of a tool;

FIG. 9 is a schematic representation of a portion of a machining system,according to some embodiments;

FIG. 10 is a schematic representation of a portion of a machiningsystem, according to some embodiments;

FIG. 11 is a schematic representation of a portion of a machiningsystem, according to some embodiments; and

FIG. 12 is a schematic side view of a tool, according to someembodiments.

DETAILED DESCRIPTION

Aspects described herein relate to improvements in tooling approachesfor machining systems utilizing machining fluids comprising asupercritical machining fluid, such as supercritical carbon dioxide(_(sc)CO₂) or supercritical nitrogen. The inventors have appreciatedthat supercritical machining fluids may provide numerous benefitscompared to conventional machining fluids, such as water-based machiningfluids, oil-based machining fluids (e.g., neat oils), minimum quantitylubrication (MQL) fluids, or synthetic machining fluids). As usedherein, a supercritical fluid refers to a fluid that is maintained aboveits critical point (i.e., at a temperature above the criticaltemperature and at a pressure above the critical pressure). For example,the critical temperature and pressure for carbon dioxide are 31.1° C.and 72.8 atm, respectively, which are readily achievable in industrialapplications. Above the critical point, distinct liquid and gas phasesdo not exist; instead, supercritical fluids exhibit characteristics ofboth liquids and gases. For example, supercritical fluids may exhibitthe flow and expansion behaviors of gasses while also being able todissolve materials like a liquid. In machining applications, rapidlyexpanding supercritical machining fluids may provide better coolingand/or more efficient heat transfer, may provide for better mixing withlubricants or dissolution of lubricants, and/or allow for the use ofsmaller amounts of lubricants compared to conventional water-basedmachining fluids

The inventors have recognized and appreciated that conventionalapproaches for tooling design may not be suitable for use withsupercritical machining fluids. In some instances, conventional toolingdesigns may achieve sufficient coverage of machining fluid over acutting interface without requiring any particular considerations forhow the machining fluid is directed towards the cutting interface. Forexample, the intrinsic mass of conventional water and/or oil-basedmachining fluids may allow the momentum of a rotating tool or workpieceto adequately spread the machining fluid across the entire cuttinginterfaces to achieve sufficient coverage. Accordingly, relativelysimple arrangements of machining fluid nozzles and/or exit orifices on atool (e.g., to simply flood the cutting interface with machining fluid)may be sufficient to achieve sufficient machining fluid coverage. Incontrast, the inventors have recognized that supercritical fluids(including supercritical machining fluids) expand rapidly upon exitingan orifice (e.g., of a nozzle and/or on a tool), and may exhibitsubstantially zero mass behavior such that little or no momentum isimparted to a rapidly expanding supercritical fluid by a rotating toolor workpiece. Consequently, the supercritical machining fluid may remainin a location corresponding to where the supercritical fluid wasdirected by a corresponding nozzle and/or orifice, and thus, sufficientcoverage of a cutting interface may not be achieved to adequately cooland/or lubricate the cutting interface.

In view of the above, the inventors have recognized and appreciatednumerous advantages with tooling that is specifically constructed andarranged to address one or more of the above-noted challenges associatedwith supercritical machining fluids. According to some aspects, toolingfor use with machining systems may be constructed and arranged to directa supercritical machining fluid towards a cutting interface to achieve adesired coverage of the supercritical machining fluid over the cuttinginterface. In particular, some aspects described herein relate totooling in which supercritical machining fluid is delivered through atool holder and/or through a tool. For example, in some embodiments, atool holder may include one or more nozzles and/or planar surfacesthrough which a flow of supercritical machining fluid exits the toolholder that are configured to direct the supercritical fluid towards thecutting interface. Alternatively or additionally, in some embodiments, atool (such as a rotatable bit) may include a plurality of outletorifices positioned along a length of the tool. For example, someorifices may be located proximally from an end of the tool, such asadjacent proximal end(s) of one or more flutes formed in the tool. Asdescribed in more detail below, such orifices may be configured todirect supercritical machining fluid along a length of the one or moreflutes. Moreover, other orifices may be positioned more distally, suchas within the one or more flutes. Depending on the particularembodiment, these various orifices may be positioned along the tool toprovide a desired coverage of the cutting interface with supercriticalmachining fluid.

In some embodiments including a tool holder with nozzles configured todirect supercritical machining fluid towards a cutting interface, thenozzles may be constructed and arranged to direct the supercriticalmachining fluid at a desired angle relative to a longitudinal axis of atool held in the tool holder. In certain embodiments, the angle for aparticular nozzle may be selected based on a target interface (e.g., acutting interface) or target area located distally from and radiallyinward from the nozzle (i.e., down the length of the tool). In someinstances, the target area may be determined based on a diameter oftool. For example, the angle of a nozzle may be selected such that thetarget area for the nozzle is positioned down the tool a distancecorresponding to between two and five times the diameter of the tool.For example the target area of the nozzle may be positioned a distanceof about three times the tool diameter down the length of the tool fromthe nozzle. Without wishing to be bound by any particular theory, theinventors have found that such arrangements may allow supercriticalmachining fluids (e.g., machining fluids comprising scCO₂) to providesufficient coverage of a cutting interface in some applications.

In some embodiments, a tool holder may have a plurality of nozzles(e.g., more than two nozzles) distributed around a circumference of thetool holder. For example, each of the nozzles may be oriented at anangle with respect to the longitudinal axis of the tool (as discussedabove) to provide a desired coverage of machining fluid around thecircumference of the tool at the cutting interface. Moreover, in someembodiments, a tool holder may include nozzles oriented at differentangles relative to the longitudinal axis of the tool. For example, somenozzles may be configured to direct supercritical machining fluid to adistal portion of the cutting interface, while other nozzles may beconfigured to direct the supercritical machining fluid to a centraland/or proximal end of the cutting interface. In one exemplaryembodiment, a first nozzle or set of nozzles may be arranged to directsupercritical machining fluid down a tool a distance corresponding tothree times a diameter of the tool, and a second nozzle or set ofnozzles may be arranged to direct the supercritical machining fluid downthe tool a distance corresponding to five times the diameter of thetool. Of course, it should be appreciated that other arrangementsincluding various combinations of distances may be suitable, as thecurrent disclosure is not limited in this regard. Moreover, in someembodiments, a configuration of nozzles (e.g., two, three, or any otherappropriate number of nozzles) may be tailored to provide a desiredamount, flow rate, and/or coverage of supercritical machining fluid fora particular cutting process.

According to some aspects, a tool for a milling or drilling operationmay include a plurality of orifices configured to deliver supercriticalmachining fluid traveling through the tool (e.g., through a cavityformed in an interior of the tool) to a cutting interface. The inventorshave recognized and appreciated that unlike with conventional machiningfluids, the configuration of such orifices can have a substantial impacton the direction in which a supercritical machining fluid is directedout of the orifices. In particular, the inventors have appreciated thatsupercritical fluids tend to be directed along a direction normal to asurface in which an orifice is formed. Accordingly, in some embodiments,a tool may include one or more recesses defining a planar surface inwhich an orifice is formed, and the orientation of the planar surfacemay be selected to provide a desired direction of travel for thesupercritical machining fluid when it exits the orifice. For example, insome embodiments, recesses may be formed having a planar surface that issubstantially normal to a direction oriented towards a cutting interfaceand/or a longitudinal axis of the tool (i.e., a direction normal to thesurface is substantially parallel to the longitudinal axis of the tool),such that supercritical fluid exiting an orifice formed in the surfaceis directed substantially parallel to the longitudinal axis of the tool.In this manner, supercritical machining fluid may be directed throughthe tool, out of the orifice, down the length of the tool, and focusedtowards a target area along the tool (e.g., a cutting interface). Forinstance, such orifices may be desirable in applications in whichdelivery of machining fluid down one or more flutes or other cuttingfeatures formed in a tool is desirable to cool and/or lubricate acutting interface associated with the flutes or cutting features.

According to some aspects, a recess formed in an outer surface of a toolalso may aid in directing supercritical machining fluid along a desireddirection, such as along the length of a tool and/or towards a cuttinginterface. For example, a recess may include walls defining a channeloriented along the desired direction. In this manner, if supercriticalmachining fluid exits an orifice formed on a surface defined by therecess along a direction other than normal to the surface (which may beoriented along the desired direction), the channel may aid inredirecting the supercritical machining fluid towards the desireddirection to aid in focusing the supercritical machining fluid towards atarget area such as a cutting interface.

Alternatively or additionally, in some embodiments, a tool may includeone or more orifices configured to direct supercritical machining fluidalong directions other than down a length of a tool. For example, incertain embodiments, one or more orifices may be configured to directsupercritical machining fluid radially outwardly, towards one or moreflutes or cutting features formed on a tool, and/or along any othersuitable direction. Depending on the particular embodiment, suchorifices may be positioned on an outer surface of a tool shank, withinone or more flutes or other cutting features formed on a tool shank(e.g., such that the orifices may deliver supercritical machining fluiddirectly to the flutes), and/or at any other suitable location on atool. In other embodiments (e.g., in fixed cutting tool applications), atool may include multiple orifices configured to direct supercriticalmachining fluid towards different portions of a cutting interface of atool.

According to some aspects, the inventors have recognized and appreciatedthat the size of the various orifices formed in a tool and/or toolholder may be selected to provide a desired combination of pressure andflow characteristics for a supercritical machining fluid. In particular,the inventors have discovered that particular ranges of orificediameters may provide desirable pressure and flow characteristics fordifferent applications to match the characteristics of other componentsof a machining system, including the pumping architecture associatedwith the supercritical machining fluid. For example, a diameter or othermaximum transverse dimension of the orifices may be greater than orequal to about 50 µm, 100 µm, 150 µm, 200 µm, and/or any otherappropriate dimension. Correspondingly, the diameter or other maximumtransverse dimension of the orifices may be less than or equal to 500µm, 400 µm, 300 µm, 200 µm, and/or any other appropriate dimension.Combinations of the foregoing are contemplated including a diameter ofthe orifices that is between about 50 microns and about 500 microns(e.g., about 150 microns). The inventors have further appreciated thatsuch orifice diameters, while providing numerous benefits when used inconnection with supercritical machining fluids as described herein, maynot be suitable for use with conventional machining fluids such aswater-based emulsions. For example, many conventional water-basedmachining fluids would likely not flow through such small orifices dueto surface tension effects, and the lubricants suspended in someconventional machining fluids (e.g., liquid CO₂) would likely clog theorifices. In contrast, supercritical machining fluids may easily flowout of such small orifices. Moreover, oils or other suitable lubricantsmay be soluble in supercritical machining fluids such as scCO₂ such thatthe oils do not clog the orifices.

In some embodiments, the diameter of the orifices may be selected basedon the number of orifices that may be required for a tool used in aparticular application. For example, in applications in which a largenumber of orifices is desirable to provide delivery of machining fluidto multiple locations along a tool and/or cutting interface, smallerdiameter holes may be beneficial. In other applications, such as gundrilling applications, fewer orifices may be used (e.g., as few as one),and correspondingly, the orifice(s) may be larger (e.g., about 500microns). Depending on the particular embodiment, such orifices (andcorresponding channels through the tool) may be formed via any suitablemethod. For example, in some instances, the orifices may be formed bylaser drilling and/or electrical discharge machining (EDM).

In addition to the above, the inventors have recognized and appreciatedthat in some applications, conventional spindle and tool holder designs(e.g., as used in milling systems) may not be suitable for use withsupercritical machining fluids. For example, many conventional spindleand tool holder designs for use with through-tool cooling arrangementsinclude a cavity located behind the tool holder that fills withmachining fluid as fluid is delivered into the tool holder, andultimately into the tool. In some applications, a coolant tube may beprovided that spans the cavity between the spindle and the tool holderto deliver machining fluid directly to the tool holder. When used withconventional machining fluids, such arrangements are generally suitable.However, the inventors have recognized that these arrangements may notbe suitable for use with supercritical machining fluids due to thepressurized nature of supercritical fluids. In particular, the inventorshave recognized that accumulation of supercritical machining fluid in acavity behind a tool holder may lead to pressurization of the cavity,which may lead to the tool holder becoming dislodged from the spindle.Even in arrangements including a coolant tube, leaking of supercriticalfluid into a cavity can lead to similar undesirable pressurization ofthe cavity behind the tool holder.

In view of the above, the inventors have recognized numerous advantagesassociated with spindle and/or tool holder configurations that can avoidsuch undesirable pressurization of a cavity behind a tool holder at atool holder-spindle attachment interface. In some embodiments, a spindlemay include one or more venting channels in communication with thecavity between the spindle and a tool holder. These one or more ventingchannels may be configured to relieve any pressure that may build up inthe cavity. In this manner, if a coolant tube leaks supercritical fluidinto the cavity, the supercritical fluid may be vented out of theventing channels to avoid buildup of pressure behind the tool holder. Insome instances, such embodiments of vented spindles may allow forcompatibility with existing tool holders (e.g., tool holders designedfor use with conventional machining fluids), which may allow such toolholders (and any associated tools) to be used in cutting operationsutilizing supercritical machining fluids.

Alternatively or additionally to the above, one or more venting channelsmay be formed in a tool holder. Similar to the embodiments discussedabove, such cooling channels may be in communication with a cavitybetween the tool holder and a spindle and configured to relieve anypressure that may build up in the cavity, e.g., as a result ofpressurized supercritical machining fluid leaking into the cavity. Insome instances, such vented tool holder arrangements may allow for theuse of supercritical machining systems with machining systems andspindles designed for use with conventional machining systems.

According to some aspects, a tool for a machining system (e.g., amilling or drilling bit) may be configured such that a supercriticalmachining fluid flows through the tool from a corresponding source ofsupercritical machining fluid for cooling and/or lubrication purposes.Such a tool may extend from a proximal end, configured to be received ina tool holder, to an opposing distal end, configured to interface with aworkpiece during a machining process. A fluid channel may extend throughat least a portion of the interior of the tool from the proximal portionof the tool towards the distal end of the tool. One or more orifices maybe formed in and extend through an outer surface of the tool such thatthe outer surface of the tool is in fluid communication with the fluidchannel. Depending on the embodiment, these orifices may be located onthe sides, on a distal portion, and/or at a distal end of the tool.During operation, supercritical machining fluid may flow into the fluidchannel through an inlet located on a proximal portion, such as aproximal end, of the tool and into the fluid channel. The supercriticalcooling fluid may then flow out from the fluid channel through each ofthe orifices in fluid communication.

When using a tool that includes channels and orifices through which asupercritical machining fluid flows, the supercritical machining fluidwill go through an expansion, and corresponding reduction in temperaturewhen it is exposed to a pressure differential that causes thesupercritical machining fluid to drop below a critical pressure of thesupercritical machining fluid. This rapid expansion and cooling of themachining fluid may cause icing in some situations which may inhibit theflow of supercritical machining fluid resulting in damage to the machinesystem, tool, and/or workpiece being machined. Thus, the expansion pointfor a supercritical machining fluid is typically located at the one ormore orifices formed in a tool that are located adjacent to a cuttinginterface between the tool and work piece. This arrangement allows theexpansion points of the supercritical machining fluid to be locatedadjacent to the location of heat generation (i.e. the cutting surface)and the supercritical machining fluid may be kept in the supercriticalstate within the interior of the tool, both of which have typically beenused to avoid icing of a tool. However, the Inventors have recognizedthat tools constructed to provide this functionality often usemanufacturing processes and/or tool designs that are not compatible withmanufacturing processes and machines that use conventionally cooledtools.

In view of the above, the Inventors have recognized a need for toolsincluding in tool delivery of a supercritical machining fluid that havebeen designed for easy manufacturing and integration with existingmanufacturing processes and/or machining systems. However, tools madefor use with conventional machining fluids use channels and orificesthat are too large for supercritical machining fluids which would resultin excessively large flow rates of the supercritical machining fluidduring a machining process. Accordingly, the Inventors have recognizedthe benefits associated with a tool including an upstream flowrestriction with a flow resistance greater than that of the one or morefluid channel and orifices located downstream from the flow restriction.This may cause the supercritical fluid to expand within the tool bodyprior to exiting through the one or more orifices of the tool onto acutting interface between a tool and a work piece. Such an arrangementis counter to the to the typical design consideration of locating theexpansion point of a supercritical machining fluid at the orificeslocated proximate to a cutting interface to avoid icing. However, theInventors have determined that the heat generated as a byproduct of themachining process is sufficient to prevent the tool and/or machiningsystem from icing even when the expansion point of the supercriticalmachining fluid is located within an interior of the tool and that thetime to icing is sufficiently long such that a machining process may beinitiated prior to icing occurring.

In view of the above, a machining tool configured to utilize asupercritical machining fluid may include a flow restriction within aproximal portion (e.g. near a shank from which the tool is attached to atool holder). The flow restriction may be upstream from and in fluidcommunication with a fluid channel and one or more orifices of the tool.Supercritical machining fluid provided by a supercritical machiningfluid source may flow into an inlet of the tool and through the upstreamflow restriction. Upon exiting the flow restriction, the supercriticalmachining fluid may expand in the one more fluid channels, or otherappropriate downstream portion, of the tool before flowing out of thetool through one or more orifices and onto a desired cutting interface.In some embodiments, a flow resistance through the one or more orificesand fluid channel may be less than the flow resistance of the flowrestriction.

As noted above, typical tools used for in tool delivery of a machiningfluid have dimensions that are inappropriate for use with supercriticalmachining fluids. However, in some embodiments, adding an upstream flowrestriction to a tool may restrict the flow of machining fluid into achannel of a tool and permit expansion to occur within the tool. Thismay enable the use of tools with relatively larger diameter orificesthat are typically used with conventional machining fluids (e.g., oil,minimum quantity lubrication (MQL) fluid, or synthetic fluids) to beused with supercritical fluids. Thus, in some embodiments, existing tooldesigns may either be modified, or retrofitted with an insert or otherattached component, to include an upstream flow restriction to enabletheir use with supercritical machining fluids.

Types of flow restrictions that may be used with the embodimentsdescribed herein may include appropriately dimensioned through holesformed in a component, nozzles, and/or any other appropriate type offlow restriction that may exhibit a flow resistance greater than the oneor more downstream channels and orifices in fluid communication with theflow restriction. The flow restrictions may also be incorporated into atool in any appropriate manner including: integral formation; an insertthat is inserted into a cavity formed in a portion of the tool; acomponent attached to a proximal portion of the tool; and/or any otherappropriate construction. In instances where a separate insert orcomponent is attached to the tool, it may be attached using a threadedconnection, a press fit, welding, brazing, and/or any other appropriatetype of connection as the disclosure is not limited in this fashion.

A flow restriction may exhibit any appropriate range of flow resistancesrelative to a combined flow resistance of a fluid channel and one ormore orifices disposed downstream from the flow restriction. Forexample, in some embodiments, a ratio of a flow resistance of a flowrestriction and a combined flow resistance of the downstream fluidchannel and one or more orifices may be greater than or equal to 4, 5,10, 20, 40, or any other appropriate ratio of the flow resistances.Correspondingly, the ratio of the flow resistances of the flowrestriction and the combined flow resistance of the downstream fluidchannel and one or more orifices may be less than or equal to 50, 40,30, or any other appropriate ratio. Combinations of the foregoing rangesare contemplated including, for example, a ratio of a flow resistance ofa flow restriction and a combined flow resistance of a downstream flowchannel and one or more offices may be between or equal to 4 and 50and/or any other appropriate combination of the foregoing. Of course, itshould be understood that ratios both greater than and less than thosenoted above are contemplated. For example, the ratio of a flowresistance of a flow restriction and a combined flow resistance of adownstream fluid channel and one or more orifices may be bounded on theupper side by channels and orifices that are sufficiently large suchthat the restriction functions as if it were exhausting directly to theexternal atmosphere. It should be understood that a tool including anupstream flow restriction may be used with any of the other embodimentsor tools and machining systems described herein.

In embodiments where it is desirable to expand a supercritical machiningfluid within the interior of a tool, appropriate combinations of thesizes of a restriction orifice and corresponding fluid channels andorifices formed in the tool may be used. For example, in one embodiment,a restriction orifice formed in a flow restriction that provides a flowpath through the flow restriction may have a maximum transversedimension (e.g. a diameter) that is greater than or equal to 50 µm, 100µm, 150 µm, 200 µm, and/or any other appropriate dimension.Correspondingly, the restriction orifice may have a maximum transversedimension that is less than or equal to 300 µm, 200 µm, 150 µm, and/orany other appropriate dimension. Combinations of the foregoing arecontemplated including a maximum transverse dimension of a restrictionorifice that is between or equal to 50 µm and 300 µm. Correspondingmaximum transverse dimensions of a fluid channel and one or moreorifices formed on an exterior surface of the tool that are in fluidcommunication with and downstream from a flow restriction may be greaterthan or equal to 500 µm, 750 µm, 1000 µm, 1500 µm, and/or any otherappropriate dimension. The maximum transverse dimension of the fluidchannel and the one or more orifices formed on the exterior surface ofthe tool may also be less than or equal to 2000 µm, 1500 µm, 1000 µm,and/or any other appropriate dimension. Combinations of the foregoingare contemplated including, for example, a maximum transverse dimensionof the fluid channel and the one or more orifices formed on the exteriorsurface of the tool that is between or equal to 500 µm and 2000 µm. Ofcourse while particular ranges of the dimensions of a restrictionorifice as well as a fluid channel and external orifices of a tool havebeen noted above, dimensions both greater than and less than thosedescribed above are also contemplated as the disclosure is not limitedin this fashion.

Without wishing to be bound by theory, supercritical machining fluidsare not compatible with every material and/or technique used in typicalmachining systems and tools due to effects such as carbonation ofmaterials; embrittlement; explosive decompression; dissolving of thematerials; and other effects. Accordingly, the various seals, O-rings,and joints and interfaces exposed to the supercritical machining fluidof a tool, toolholder, components attached to a toolholder (e.g. coolantpipe, collet, etc.), a spindle, and/or any other appropriate componentof a machining system may include materials that are selected to becompatible with the supercritical machining fluid such that thesecomponents and systems may be configured for operation with thesupercritical machining fluid as compared to typical systems which maynot be compatible with the supercritical machining fluid. For example,materials may be selected based on the operating temperature andpressure ranges associated with the supercritical fluid as well as toprovide compatibility with the supercritical fluid. For example,operating pressures may be between about 100 and 140 bar, and in someinstances, up to about 200 bar, 300 bar, 400 bar or more, and operatingtemperatures may be between about 20° C. and about 100° C. In someembodiments, suitable materials for seals and O-rings that can operatein these pressure and temperature ranges and also provide compatibilitywith supercritical fluids such as scCO2 include, but are not limited to,perfluoroelastomers (e.g.Kalrez 0090), hard durometer fluoroelastomers(e.g. hard durometer Viton and Viton encapsulated with fluorinatedethylene propylene), hydrogenated acrylonitrile butadiene rubber, andpolytetrafluoroethylene (PTFE). In some applications, it may bebeneficial to select the highest durometer available of a seal or O-ringformed from a suitable material. Moreover, joints that may be suitablefor connecting various portions of the systems described herein include,but are not limited to, hydraulic joints such as National Pipe Thread(NPT), British Standard Pipe (BSP and/or BSPP), Joint Industrial Council(JIC), and/or other compression fittings rated to greater than or equalto 200 bar.

For the sake of clarity, a majority of the embodiments described hereinare described relative to rotational machining systems that include arotating toolholder and tool held in the toolholder with correspondingflows of supercritical machining fluid routed through one or both ofthese components. However, it should be understood that the variousembodiments described herein may be used with any appropriatecombination of rotational and/or rotationally stationary tools and/ortoolholders as the disclosure is not limited in this fashion.

Turning to the figures, specific non-limiting embodiments are describedin further detail. It should be understood that the various systems,components, features, and methods described relative to theseembodiments may be used either individually and/or in any desiredcombination as the disclosure is not limited to only the specificembodiments described herein.

FIG. 1 is a perspective view of one embodiment of a tool 100 inaccordance with some aspects described herein. In particular, tool 100,which may be configured as a milling tool and/or for use with amachining center, includes a distal end 102 and a proximal end 104(e.g., a shank of the tool 100), which may be received in a tool holderof a machining system (not depicted). The tool 100 includes a pluralityof flutes 106 separated by channels 108. The flutes may include cuttingedges that define at least a portion of a cutting interface when thetool is in use in a machining system. In the depicted embodiment, theflutes 106 extend helically along the tool; however, it should beunderstood that other flute configurations may be suitable, as thecurrent disclosure is not limited to any particular configuration offlutes 106 and channels 108. For example, in other embodiments, theflutes may be substantially linear.

The tool includes a plurality of orifices 110 that are in fluidcommunication with a central fluid channel formed through at least aportion of the tool (e.g., see FIG. 2 ). In this manner, supercriticalmachining fluid delivered into the central fluid channel at the proximalend of the tool may be delivered to the cutting interface via orifices110 where the supercritical machining fluid exits along lines 112. Forclarity, not every line 112 is labeled in FIG. 1 . As illustrated, atool may include a plurality of orifices formed on surfaces of the toolhaving different orientations such that supercritical machining fluidexits the tool along a plurality of different directions (indicated bythe lines 112) to provide a desired coverage of supercritical machiningfluid for a particular machining application. Each line 112 is generallyperpendicular to a surface on the tool where a corresponding orifice 110is formed. For example, orifices 110 may be formed in channels 108 suchthat the supercritical machining fluid is directed towards the cuttingedges of the flutes 106. Further, as elaborated on further below, insome embodiments, a surface of the tool body surrounding these orificesmay be planar and/or recessed to facilitate controlling a direction ofthe flow of supercritical machining fluid. In some instances, one ormore orifices may be formed on a distalmost surface, which may be normalto a longitudinal axis of the tool, such that supercritical machiningfluid exits the distal tip parallel to the longitudinal axis of thetool.

In view of the above, the it should be understood that the plurality oforifices formed in a tool body may be positioned on any number ofsurfaces of a tool body and oriented in a number of desired directions.Including, for example, one or more orifices of the plurality oforifices may be located on: a side surface of the tool body extendingbetween the proximal and distal ends of a tool body; a distal surface ofthe tool body; and/or any other appropriate portion of the tool body.Additionally, the orifices may be configured to direct the streams ofsupercritical machining fluid towards any appropriate cutting interfacewhich may either be located at a distal end of the tool body and/orradially outwards from the total body as described above in regards tothe embodiment including orifices configured to direct supercriticalmachining fluid in a direction that includes a component that isdirected radially outwards towards an interface between the flutes and aworkpiece.

FIG. 2 is a side view of the tool 100 of FIG. 1 . As noted above, tool100 includes a central fluid channel in communication with each of theorifices 110, and as illustrated in FIG. 2 , the central fluid channelmay have a machining fluid inlet 114 at the proximal end 104 of thetool. In this manner, supercritical machining fluid may be deliveredinto and transported through the tool 100 before exiting the orifices110 to provide desired cooling and/or lubrication of a cuttinginterface.

FIG. 3 is figure of one embodiment of a tool 300 similar to tool 100discussed above during operation. In particular, tool 300 is secured ina tool holder 320, which is secured to a spindle 330 of a machiningsystem. FIG. 3 further depicts supercritical machining fluid 350 (suchas scCO₂) exiting from a plurality of orifices formed in the tool 300.

Referring now to FIGS. 4-5 , another embodiment of a tool 400 isdescribed in more detail. Similar to the embodiments discussed above,tool 400 includes a distal end 402 and a proximal end 404, which may beattached to a tool holder to secure the tool 400 in a machining system.The tool 400 further includes a plurality of flutes 406 separated bychannels 408. In this embodiment, a plurality of orifices 410 are formedon planar surfaces 412 of recesses 414 cut into the tool. In particular,the recesses 414 are formed such that the planar surfaces 412 are normalto a longitudinal axis of the tool 400, and similar to the embodimentsdiscussed above, each orifice 410 is in fluid communication with acentral fluid channel (not depicted) formed in the tool 400. In thismanner, supercritical machining fluid exiting the orifices 410 isdirected along a direction parallel to the longitudinal axis, thoughother orientation directions are also contemplated. In some instances,the recesses 414 (and corresponding orifices and planar surfaces 412)may be positioned such that the supercritical machining fluid isdirected distally and towards the flutes 406, such that thesupercritical machining fluid may flow distally down the flutes 406.Moreover, as noted above, in some instances, the recesses 414 may beconfigured to aid in guiding supercritical fluid exiting from orifices410 along a desired direction, such as down a length of the tool 400. Insome embodiments, tool 400 may include secondary orifices 420 (e.g.,formed in channels 408) such that supercritical machining fluid isdirected at least partially radially outwardly from the tool (e.g.,along lines 416).

FIG. 6 depicts a portion of a machining system according to someembodiments. In particular, FIG. 6 shows a tool 600 secured in a toolholder 620, which is secured in a spindle 630. As shown in the Figure,the tool holder 620 includes a plurality of nozzles 622 configured todirect supercritical machining fluid towards a cutting interface of thetool 600. As discussed above, in some embodiments, the nozzles 622 maybe configured to direct the supercritical machining fluid 650 at anangle relative to the longitudinal axis of the tool 600. For example,the nozzles may be oriented such that the supercritical machining fluid650 contacts the tool at a position spaced from the nozzles by adistance corresponding to between about two and five times a diameter ofthe tool 600.

While some of the above-described embodiments may be related torotatable tools (e.g., mills or similar machining tools), it should beunderstood that the current disclosure is not limited in this regard.For example, FIGS. 7-8 show schematic side views of cutting tools 700and 800, respectively, which may be stationary cutting tools for use inconnection with machining systems configured to rotate a workpiece(e.g., a lathe or similar system). As shown in FIG. 7 , orifices 710 and720 are simply formed in top and flank surfaces of the tool 700. As aresult, supercritical fluid flowing into the top orifice along direction712 exits along a direction that diverges from direction 712 (adirection that is generally perpendicular to the surface in whichorifice 710 is formed. Similarly, supercritical fluid flowing into theflank orifice 720 along direction 722 exits along a direction thatdiverges from direction 722.

In contrast, the tool 800 shown in FIG. 8 includes a first surface 814on which the top orifice 810 is formed, and a second surface 824 onwhich the flank orifice 820 is formed. The first surface is orientednormal to the direction 812, such that supercritical machining fluidexiting orifice 810 is parallel to direction 812. Similarly, the secondsurface 824 is oriented normal to direction 822 such that thesupercritical machining fluid exiting orifice 820 is directed along adirection parallel to direction 822. In this manner, the surfaces 814and 824 may allow for the supercritical machining fluid to be directedalong two or more directions, as desired, to achieve desired coverage,lubrication, and/or cooling of a cutting interface. Moreover, tool 800may include recesses 816 and 826 associated with orifices 810 and 820,respectively. The recesses may be configured to provide a clearancearound each orifice such that supercritical machining fluid exiting theorifices is not inadvertently directed away from directions 812 and 822.Additionally, in some instances, the recesses 816 and 826 may aid indirecting the supercritical machining fluid along directions 812 and822.

Referring now to FIG. 9 , one embodiment of a machining system 900 isdescribed in more detail. In the depicted embodiment, the machiningsystem includes a tool 902 held in a tool holder 904, which is securedin a spindle 906. A drawbar 908 may extend through the spindle 906 toassist with securing the tool holder 904 and tool 902 to the spindle906. In the depicted embodiment, a coolant tube 910 extends between thedrawbar 908 and the tool holder 904 to deliver supercritical machiningfluid 950 traveling through the drawbar 908 into the tool holder 904,and through the tool 902 (e.g., via channels 916 formed through thetool) before the machining fluid 950 is delivered out of the tool to acutting interface. The coolant tube 910 may be secured to the drawbar908 and tool holder 904 via one or more bushings 912 and/or seals 914(such as O-rings). However, as noted previously, even with such sealingarrangements associated with a coolant tube, supercritical machiningfluid may leak into a cavity 920 between the spindle 906 and tool holder904. Accumulation of pressurized supercritical machining fluid in thecavity 920 cause a build-up of pressure behind the tool holder 904,which may undesirably cause the tool holder 904 to become dislodged fromthe spindle 906.

In view of the above, in the depicted embodiment, the spindle 906 mayinclude one or more venting channels 922 configured to provide apressure relief for the cavity 920. Specifically, the venting channelsare in fluid communication with the cavity 920 and an exterior of thespindle 906 and tool holder 904 such that any supercritical machiningfluid 950 that may inadvertently leak into the cavity 920 may exit outof the venting channels 922. In this manner, pressure is not able tobuild up behind the tool holder as a result of supercritical fluidleaking into the cavity 920. While the venting channels 922 are shown asbeing formed in the spindle, it should be appreciated that otherarrangements may be suitable. For example in other embodiments, ventingchannels may be formed in the tool holder 904 in addition to, or as analternative to, the venting channels 922 formed in the spindle 906.

FIG. 10 depicts a second embodiment of a machining system 1000configured to utilize a supercritical machining fluid. In the depictedembodiment, the machine system includes a tool 1002 held in a toolholder 1004, which is secured to a spindle 1006. In FIG. 10 ,supercritical machining fluid 1050 flows through a coolant tube 1010from the spindle 1006 into the tool holder 1004, and through channels1016 formed in the tool 1002. In this embodiment, supercriticalmachining fluid 1050 is delivered out of the tool 1002 to a cuttinginterface. Bushings 1012 and/or seals 1014 (such as O-rings) may beconfigured to support and seal the coolant tube 1010. As notedpreviously, even with such sealing arrangements associated with thecoolant tube 1010, supercritical machining fluid may leak into a cavity1020 between the spindle 1006 and the tool holder 1004. Accumulation ofpressurized supercritical machining fluid in the cavity 1020 may cause abuild-up of pressure behind the tool holder 1004, which may undesirablycause the tool holder 1004 to become dislodged from the spindle 1006.

Accordingly, in the depicted embodiment, tool holder 1004 includesventing channels 1022 configured to provide a pressure relief for thecavity 1020. Specifically, the venting channels are in communicationwith the cavity 1020 and an exterior of the tool holder 1004 such thatany supercritical machining fluid 1050 that may inadvertently leak intothe cavity 1020 may exit out of the venting channels 1022. In thismanner, pressure is not able to build up behind the tool holder as aresult of supercritical fluid leaking into the cavity 1020. While theventing channels 1022 are shown as being formed in tool holder 1004, itshould be appreciated that other arrangements may be suitable. Forexample in other embodiments, venting channels may be formed in thespindle 1006 in addition to, or as an alternative to, the ventingchannels 1022 formed in the tool holder 1004.

FIG. 11 shows an alternate embodiment of a machining system 1000configured to utilize a supercritical machining fluid similar to thatdescribed in FIG. 10 . However, in the current embodiment the toolholder includes fluid paths 1118 formed in the tool holder 1104 whichare also used to deliver supercritical machining fluid 1150 to theinterface between the tool 1102 and a workpiece. Specifically,supercritical machining fluid 1150 flows though the coolant tube 1110from the spindle 1106, into the tool holder 1104, and through channels1116 formed in the tool 1102 and channels 1118 formed in the tool holder1104. In this embodiment, supercritical machining fluid 1050 isdelivered out of the tool 1102 and the tool holder 1104 to a cuttinginterface. Bushings 1112 and/or seals 1114 (such as O-rings) may beconfigured to support and seal the coolant tube 1110. As notedpreviously, even with such sealing arrangements associated with acoolant tube, supercritical machining fluid may leak into a cavity 1120between the spindle 1106 and the tool holder 1104. Accumulation ofpressurized supercritical machining fluid in the cavity 1120 may cause abuild-up of pressure behind the tool holder 1104, which may undesirablycause the tool holder 1004 to become dislodged from the spindle 1106.

Accordingly, in the depicted embodiment, the tool holder 1104 includesventing channels 1122 configured to provide a pressure relief for thecavity 1120. Specifically, the venting channels are in communicationwith the cavity 1120 and an exterior of the tool holder 1104 such thatany supercritical machining fluid 1150 that may inadvertently leak intothe cavity 1120 may exit out of the venting channels 1122. In thismanner, pressure is not able to build up behind the tool holder 1104 asa result of supercritical fluid leaking into the cavity 1120. While theventing channels 1122 are shown as being formed in tool holder 1104, itshould be appreciated that other arrangements may be suitable. Forexample in other embodiments, venting channels may be formed in thespindle 1106 in addition to, or as an alternative to, the ventingchannels 1122 formed in the tool holder 1104.

In addition to the above, the tool holder 1104 includes recesses 1119that have been formed on a surface of the tool holder oriented towards acutting interface between the tool 1102 and a workpiece (notillustrated). As noted above, the supercritical machining fluid 1150tends to be oriented in a direction that is normal to a surface throughwhich it exits. Accordingly, the recesses may have a planar surface in alocation where the outlets of the channels 1118 formed in the toolholder are located. Further, these planar surfaces may be oriented in adirection that is normal to a direction of flow of the supercriticalmachining fluid within the channel proximate to the outlets.Alternatively or additionally, these planar surfaces formed on a distalportion of the tool holder and associated with the channels may beoriented so that they are normal to a distal direction oriented towardsthe cutting interface. Depending on the particular embodiment, thedirection may include both a component oriented in the distal directionand a radial component such that the direction is angled relative to alongitudinal axis of the tool holder and tool. This radial component mayeither be oriented in a radial direction outwards from the tool and toolholder and/or inwards towards a central axis passing through the tooland tool holder as depicted in the figure. In either case, the use ofone or more planar surfaces associated with one or more channels formedin the tool holder may provide a desired flow of supercritical machiningfluid from the tool holder to a desired cutting interface duringoperation.

In the above embodiment, the use of planar surfaces which may be formedin corresponding recesses, or in another appropriate surface feature ofa tool holder, are used to direct a flow of supercritical machiningfluid in a desired direction. However, embodiments in which one or morenozzles positioned on a distal portion of a tool holder and in fluidcommunication with the one or more channels 1118 in the tool holdertransporting the flows of supercritical machining fluid 1150 are alsocontemplated. For example, the nozzles which may have a taperingcross-sectional profile that narrows towards a distal tip of the nozzlemay be used to direct a flow of supercritical machining fluid towards adesired cutting interface in the directions noted above. The nozzles maybe attached to a distal portion of a tool holder using any appropriateconnection including, threaded connections, welding, mechanicalinterlocking features, and/or any other appropriate connection. Further,the nozzles may either be permanently attached to the tool holder and/ormay be removable as the disclosure is not limited in this fashion.

FIG. 12 is a side view of one embodiment of a tool 1200 in accordancewith some embodiments. In particular, the tool 1200, which may beconfigured as a milling tool and/or for use with a machining center,though other machining tools are also contemplated. The tool includes adistal end 1202 and a proximal end 1204 (e.g., a shank of the tool1200), which may be received in a tool holder of a machining system (notdepicted). In the embodiment of FIG. 12 , a supercritical machiningfluid 1250 flows through an inlet of the tool which in the depictedembodiment is an inlet of a flow a restriction 1230. The flowrestriction may be located in a proximal portion, or end, of the tool.However, embodiments in which the flow restriction is distanced from aproximal end of the tool are also contemplated.

After flowing into the flow restriction 1230, the supercriticalmachining fluid may flow into a fluid channel 1216 that is downstreamfrom and in fluid communication with the flow restriction. The channelmay have an increased diameter and a correspondingly decreased flowresistance as compared to the flow restriction. Accordingly, thesupercritical machining fluid may expand within the fluid channel. Oncethe supercritical machining fluid 1250 has expanded in the fluid channel1216, it may flow out through one or more orifices that are formed inthe tool and in fluid communication with the fluid channel. For example,in one embodiment, a plurality of first orifices 1210 located on aportion of the tool distanced from a distal end of the tool and/or oneor more second orifices 1220 formed on a distal end of the tool may beused to direct the flow of expanded supercritical machining fluid onto adesired cutting interface. As shown, each of the orifices 1210 and 1220are configured such that the expanded supercritical machining fluid 1250is delivered to the cutting interface in a direction substantiallyparallel to a longitudinal axis of the tool 1200. However, embodimentsin which the supercritical machining fluid is directed in a directionthat is angled relative to the longitudinal axis of the tool are alsocontemplated.

In the embodiment depicted in FIG. 12 , the flow restriction 1230 isprovided as an insert that is disposed in a correspondingly sized andshaped cavity formed in a proximal portion of the tool 1200. Forexample, the fluid restriction may be a valve, or other construction,that is threaded into a threaded recess formed in a proximal portion ofthe tool 1200 via threads 1218 though any other appropriate type ofconnection may be used as previously noted. The flow restriction isupstream from and in fluid communication with one or more fluid channels1226 that extend at least partially, and in some instances entirely,along a length of the tool. The one or more fluid channels are in fluidcommunication with one or more corresponding orifices 1210 and 1220either distanced from or located at a distal end of the tool. As notedabove, the flow resistance of flow restriction 1230 may be greater thanthe flow resistances of the fluid channel and one or more orifices ofthe tool.

In the above embodiment, the flow restriction 1230 is threaded into thetool 1200. However, it should be appreciated that any suitable couplingcan be used. For example, in other embodiments, a flow restriction maybe connected to the tool using a press fit, welding, brazing, and/or anyother appropriate type of connection as the disclosure is not limited inthis fashion. Additionally, embodiments in which a flow restriction isintegrally formed with a tool are also contemplated.

In the embodiment depicted in FIG. 12 , the flow restriction 1230 has astraight narrow orifice 1228 extending through the flow restriction.However, it should be understood that a flow restriction may have anyappropriate construction capable of operating in the described fashionincluding, for example, nozzles in fluid communication with a fluidchannel of the tool and/or any other appropriate construction. Further,different types of flow restrictions may be desirable depending on thetype of tool, workpiece, or supercritical machining fluid compositionbeing used.

Various aspects of the present disclosure may be used alone, incombination, or in a variety of arrangements not specifically discussedin the embodiments described in the foregoing and is therefore notlimited in its application to the details and arrangement of componentsset forth in the foregoing description or illustrated in the drawings.For example, aspects described in one embodiment may be combined in anymanner with aspects described in other embodiments. Thus, while thepresent teachings have been described in conjunction with variousembodiments and examples, it is not intended that the present teachingsbe limited to such embodiments or examples. On the contrary, the presentteachings encompass various alternatives, modifications, andequivalents, as will be appreciated by those of skill in the art.Accordingly, the foregoing description and drawings are by way ofexample only.

Also, some embodiments described herein may be embodied as a method, ofwhich an example has been provided. The acts performed as part of themethod may be ordered in any suitable way. Accordingly, embodiments maybe constructed in which acts are performed in an order different thanillustrated, which may include performing some acts simultaneously, eventhough shown as sequential acts in illustrative embodiments.

Further, some actions may be described as taken by a “user.” It shouldbe appreciated that a “user” need not be a single individual, and thatin some embodiments, actions attributable to a “user” may be performedby a team of individuals and/or an individual in combination withcomputer-assisted tools or other mechanisms.

What is claimed is:
 1. A machining method comprising: flowing asupercritical machining fluid through a flow restriction of a tool bodyinto a fluid channel of the tool body; expanding the supercriticalmachining fluid in the fluid channel; and flowing the expandedsupercritical machining fluid though one or more orifices formed on anouter surface of the tool body, wherein a flow resistance of the one ormore orifices and the fluid channel is less than a flow resistance ofthe flow restriction.
 2. The method of claim 1, wherein the one or moreorifices are a plurality of orifices, wherein at least a portion of theplurality of orifices are formed within a plurality of grooves, andwherein the groves separate a plurality of flutes located at a distalportion of the tool body.
 3. The method of claim 1, further comprisingdirecting the expanded supercritical machining fluid out of the one ormore orifices in a first direction at least partially parallel to alongitudinal axis of the tool body.
 4. The method of claim 1, furthercomprising directing the expanded supercritical machining fluid out ofthe one or more orifices towards a cutting interface between the toolbody and a workpiece.
 5. The method of claim 1, wherein thesupercritical machining fluid comprises supercritical carbon dioxide. 6.The method of claim 1, wherein each orifice of the one or more orificeshas a diameter between about 50 microns and about 500 microns.
 7. Themethod of claim 1, wherein a ratio of a flow resistance of the flowrestriction and a combined flow resistance of the fluid channel and oneor more orifices is greater than or equal to
 4. 8. The method of claim1, wherein flowing the supercritical machining fluid through therestriction comprises flowing the supercritical fluid through an insertto the tool body wherein the insert comprises the flow restriction. 9.The method of claim 1, wherein the flow restriction is upstream from andin fluid communication with the fluid channel.
 10. The method of claim1, wherein at least one of the one or more orifices is formed in arecess formed along an outer surface of the tool body, and at least someof the supercritical machining fluid is flowed through the recess viathe at least one orifice formed in the recess.
 11. The method of claim1, wherein at least one orifice of the one or more orifices is locatedon a side surface of the tool body.
 12. The method of claim 1, furthercomprising directing at least some of the expanded supercriticalmachining fluid out of a first orifice of the one or more orifices in adirection perpendicular to a surface of the tool body in which the firstorifice is formed.
 13. The method of claim 1, wherein the one or moreorifices are formed in one or more planar surfaces formed on an outersurface of the tool body.
 14. The method of claim 13, wherein at leastsome of the planar surfaces are normal to a longitudinal axis of thetool body and/or a direction oriented towards a cutting interface of thetool body.
 15. A machining system comprising: a tool holder constructedand arranged to receive a tool and secure the tool within the toolholder, wherein the tool is configured to deliver a supercriticalmachining fluid to a cutting interface through the tool; and a spindleconstructed and arranged to receive the tool holder, wherein a cavityformed between the tool holder and the spindle is in fluid communicationwith an exterior of the machining system.
 16. The machining system ofclaim 15, wherein the spindle comprises one or more venting channelsextending between the cavity and an exterior of the spindle.
 17. Themachining system of claim 15, wherein the tool holder comprises one ormore venting channels extending between the cavity and an exterior ofthe tool holder.
 18. The machining system of claim 15, wherein thesupercritical machining fluid comprises supercritical carbon dioxide.19. The machining system of claim 15, further comprising: a tool securedwithin the tool holder, the tool comprising: a tool body a flowrestriction in the tool body, wherein the flow restriction is upstreamfrom and in fluid communication with a fluid channel; and one or moreorifices in fluid communication with a fluid channel, wherein a firstorifice of the one or more orifices is configured to directsupercritical machining fluid out of the first orifice along the firstdirection; wherein the flow restriction is configured to expand thesupercritical machining fluid as it flows through the flow restriction.20. The machining system of claim 19, wherein the one or more orificesare configured to expand the supercritical machining fluid out of theone or more orifices in a first direction substantially parallel to alongitudinal axis of a tool body of the tool.
 21. The machining systemof claim 19, wherein the orifices are configured to direct the expandedsupercritical machining fluid out of the one or more orifices towards acutting interface.
 22. The machining system of claim 19, wherein thesupercritical machining fluid comprises supercritical carbon dioxide.23. The machining system of claim 19, wherein each orifice of the one ormore orifices has a diameter between about 50 microns and about 500microns.
 24. The machining system of claim 19, wherein a ratio of a flowresistance of the flow restriction and a combined flow resistance of thefluid channel and one or more orifices is greater than or equal to 4.